Ultrasonic Sensor Array for Anti-Spoofing Biometric Authentication
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Solution Overview
Problem
Current biometric systems, particularly those using fingerprint authentication, are vulnerable to spoofing attacks where counterfeit fingerprint patterns are created using materials like silicone rubber or gelatin, which can deceive the sensors and compromise security.
Innovation Solution
The implementation of an ultrasonic sensor array and control system that captures both surface and sub-epidermal features of a finger, using different acquisition time windows to differentiate between genuine and spoofed fingerprints by analyzing temporal-based feature differences and liveness indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fingerprint sensors are used, then authentication is simple and fast, but the system is vulnerable to spoofing attacks using materials like silicone rubber or gelatin
Solution Approach 1:
The patent replaces traditional optical or capacitive fingerprint sensing with ultrasonic sensing technology. The ultrasonic sensor array emits acoustic waves that penetrate the fingerprint layer and reflect off sub-epidermal features, enabling detection of genuine biological tissue properties that spoofing materials cannot replicate. This mechanical wave-based approach substitutes the previous electromagnetic or optical fields, providing inherent anti-spoofing capabilities through depth-resolved imaging.
Solution Approach 2:
The invention transitions from two-dimensional surface fingerprint scanning to three-dimensional depth-resolved imaging of sub-epidermal features. By capturing ultrasonic reflections at multiple depths and processing them through focus metrics, the system creates a volumetric representation of fingerprint ridges and valleys beneath the skin surface. This dimensional extension allows authentication based on internal tissue structure rather than just surface patterns.
2Measurement precision
If ultrasonic sensor array with multiple acquisition time windows is used, then spoofing detection accuracy is improved, but processing time and computational load increase
Solution Approach 1:
The system performs preliminary acquisition of multiple ultrasonic echo signals with different time windows during the authentication process. By collecting depth-resolved data from multiple time gates simultaneously or in rapid succession, the system prepares comprehensive raw data that can be processed through focus metric calculations. This preliminary data gathering enables subsequent rapid analysis without requiring sequential repeated measurements.
Solution Approach 2:
The patent employs multiple acquisition time windows that capture more echo signal data than strictly necessary for basic fingerprint matching. By acquiring excessive temporal data across different depth ranges, the system ensures that sufficient signal-to-noise ratio and depth information are obtained for robust focus metric calculation, even in challenging conditions. This partial redundancy provides computational headroom for accurate spoof detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances authentication security by reliably distinguishing between real and fake fingerprints, providing a higher level of assurance against spoofing attempts and improving user validation processes.
Implementation Method 1
The control system is configured to acquire first image data generated by the ultrasonic sensor array corresponding to a first reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from the target object
Implementation Method 2
The integrated circuit includes a transmitter circuit configured to provide a first signal to the sensor array and a receiver circuit configured to receive a second signal from the sensor array. The sensor array includes an ultrasonic transmitter configured to generate the ultrasonic wave in response to the first signal and a piezoelectric receiver layer configured to detect a reflection of the ultrasonic wave.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An apparatus may include an ultrasonic sensor array and a control system. The control system may be configured to acquire first image data generated by the ultrasonic sensor array corresponding to at least one first reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from a target object during a first acquisition time window. The control system may be configured to acquire second image data generated by the ultrasonic sensor array corresponding to at least one second reflected ultrasonic wave received by at least a portion of the ultrasonic sensor array from the target object during a second acquisition time window that is longer than the first acquisition time window. The control system may further be configured to initiate an authentication process based on the first image data and the second image data.